Formation of Mt. Fuji

The beautiful and almost perfectly cone-shaped structure of Mt. Fuji that we see today was formed after three generations of volcanic activity---the Mt. Ashitaka and Komitake volcanoes that are believed to have become extinct more than 100,000 years ago; the Older Fuji Volcano that is thought to be have been active up until about 10,000 years ago; and the Younger Fuji Volcano that started erupting about 10,000 years ago.
Origin of the name Mt. Fuji

There are several theories regarding the origin of the name Mt. Fuji.

Some assumptions are that it was derived from the Japanese word fuji-yama (不二山) meaning a mountain "second to no other" in height; or from fujin-yama (不尽山) meaning "a mountain that surpasses all others in size"; or from funchi in the Ainu (an ethnic group indigenous to Northern Japan) language meaning "the god of fire" or a "volcano." Another explanation traces the origin of the name to the Japanese folk tale The Moon Princess, in which the moon princess leaves the old couple that brought her up on Earth and returns to the moon.

When the heartbroken old man burnt the elixir she had left behind on the slopes of the mountain, he noticed smoke rising out from the top of the mountain.

Thus the mountain came to be called Mt. Fuji, from the Japanese word for immortality, fushi (不死).